I've got a WOLF that I had on a '90 Chevy pickup I restored for 2-years now. I'll buy another one the second this one gets messed-up. It's soft on the inside, repels water on the outside (though, it's not totallly waterproof). Plus, it's thick, so it protects from my idiot neighbors in our community parking lot. I'd guess you don't want "waterproof" anyway, since it would tend to trap-in moisture as well as it blocks-out. 1-hour in sunshine, and this thing is bone-dry, whether it's left on the truck or not.
I had one of those Tyvek-style covers for a 91 Trans-Am Convertible I had. Those work nice too, at keeping out sun/water, but they're so thin they don't offer much protection from car-doors or hail.
Spend the extra $20 and get the cable plus lock. I've got nerf-bars on my truck, so the cable-lock works great for me. If you don't have a cable, wind and lookie-loos will take away any high-buck cover. And you don't look too smart pulling your cover out of a tree.